As a straight conveying device which can respond to vacuum, such devices are known that is provided with a magnet coupling type non-contact transmission method at a driving force transmission portion and a contact support method such as a sliding bearing and a ball bush at a contact portion (See Patent Document 1, for example).
However, when the contact portion is of a contact support type, there is a problem of a lowered work processing productivity due to limitation on a shift to a higher driving speed in order to avoid drop of cleanliness caused by dust generated with rise of a driving speed and of durability due to progress of bearing abrasion.
Also, such a device is publicly known that a conveying rod is inserted into a vacuum process chamber through an opening provided at the vacuum process chamber, the opening and the conveying rod are sealed by a differential exhaust seal and the differential exhaust seal is constituted in the same housing as a housing of a static-pressure gas bearing supporting the conveying rod (See Patent Document 2, for example).
However, in the device described in Patent Document 2, air flowing out of the static-pressure gas bearing is directly discharged into a chamber where the conveying device is installed, and since the conveying rod is supported by a contact support type bearing such as a ball bush other than the static-pressure gas bearing, generation of dust can not be prevented basically, and the dust generation is increased with rise of the rod driving speed, which lowers the cleanliness of a clean room where the device is installed and durability of the device is lowered by progress of the bearing abrasion, which is a problem.
Japanese Unexamined Patent Application Publication No. 7-205078
Japanese Unexamined Patent Application Publication No. 2002-303323